EFFECTS OF DDT ON LABELLAR RECEPTORS IN 2 DDT-RESISTANT AND 2 DDT-SUSCEPTIBLE STRAINS OF HOUSE-FLIES

Electrophysiological responses of labellar hairs of resistant and susceptible strains of the house fly were recorded at times following treatment of the hairs with DDT. Under the influence of DDT, the receptors of a hair discharged groups of impulses in high-frequency trains instead of the usual regular volley. The effect was observed to gradually spread to nontreated hairs. Among four strains chosen for gradation from high resistance to high susceptibility, in general the relative effectiveness of DDT corresponded to overall resistance as indicated by LD50 data. The highly resistant strain showed essentially no effects, and the other strains showed effects with some degree of recovery. Results for the highly susceptible strain were anomalous in not differing significantly from those of the moderately resistant strai. Unexpectedly small effects in the highly susceptible strain point to a strain characteristic not necessarily correlated with LD50 data. © 1979.